Digital signal recording devices such as those attached to host processors record records as single addressable units in magnetic tape subsystems. Such addressable units are a block of signals recorded on the tape as set forth in the documents incorporated by reference. Each such block on a tape is separated by a so-called inter-block gap (IBG) which can be an erased portion of the tape, a tone or other special symbol denoting such IBG. Generally the IBG's are quite long, i.e., greater than 0.1 centimeter. When a large number of small records are recorded, then the IBG's occupy a major portion of the magnetic tape resulting in reduced storage capacity. It is desired to provide for a more efficient method, apparatus and format for recording small records, particularly records of variable or indeterminate length when initially received. That is, the length of a record is determined by the host processor for each file which may consist of many records. All of the records in one file usually are the same length, for example 973 bytes, in another file to be recorded on the same tape the record length could be different, for example 3300 bytes, no limitation thereto intended. In yet another file a record could be 64,000 bytes. It is desired to provide an enhanced recording format without software intervention by a host processor. It is also desired to provide for different length records to be recorded on the same tape without intervention by a host processor and to faithfully reproduce the combined records into one block after recording.
A similar problem arises on magnetic and optical disks using fixed block architecture. In such architecture, each track is divided into a large plurality of equal sized sectors, each sector capable of storing a predetermined number of bytes, such as 2048 bytes. Recording a large number of small records on such a track, for example a record of 333 bytes requires 2024 bytes of disk space for each of the 333 byte records. This means that a little over 1600 bytes are wasted in each sector. Similarly, in count key data (CKD) format which has no identifiable sectors, each small record recorded in that format is separated by interblock gaps using the same principles set forth in tapes, as described in the documents incorporated by reference. The invention can be applied to such disk or other recorders in the same manner as applied to magnetic tape.